VonGlaus;
I feel your pain, LOL. I love good FPS games but have decided that offline, singleplayer is where I belong. I like all the games bybyx mentions and I will still make the occasional foray into games such as Day of Defeat Source but as you mentioned there are waaaay too many young "dudes" out there who obviously spend every waking minute playing and either know every map intimately by heart or have some cheat method intiated which makes playing less fun and therefore unsatisfying and pointless. Tactics? Cooperation? No way, dude!
IMHO if someone could come up with an FPS that generates a completely new, random map each time and wouldn't permit cheating then I think us oldtimers might have a better shot (pun intended), LOL. As it is, I play COD2 online but only with some friends for my online fix.
That's one of the attractions of SHIII and SHIV, they are games that demand patience and a bit of thought/analysis but can still crank the tension up. Definitely not for the MTV types, LOL.